I observed a tae kwon do cl and I have a question concerning it. There was a BLACK BELT man in the cl?

and I observed his techniques. With all due respect his kicks, punches & techniques resembled a WHITE BELT & I do not say that with exaggeration. How is this possible? I realize that black belt students are not perfect but his lacked power in his punches, I mean absolutely nothing. I do not say this in a condescinding manner but only to gather some input on how can a black belt man in a cl actually look like a white belt? How could he get a black belt? Is there something inherently wrong with the instructor or what? The instructor is 5th Dan Hapkido & 7th Dan TKD. Please shed some light on this.